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A188050 a(n) = A016755(n) - A001845(n). 1
0, 20, 100, 280, 600, 1100, 1820, 2800, 4080, 5700, 7700, 10120, 13000, 16380, 20300, 24800, 29920, 35700, 42180, 49400, 57400, 66220, 75900, 86480, 98000, 110500, 124020, 138600, 154280, 171100, 189100, 208320, 228800, 250580, 273700 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
A016755 are odd cubes and A001845 are centered octahedral numbers, so the sequence might be regarded as odd cubes without their octahedral content.
A000330 are square pyramidal numbers.
LINKS
FORMULA
a(n) = (10/3)*n*(n + 1)*(2*n + 1).
a(n) = 20 * A000330(n).
G.f.: 20*x*(1+x)/(1-x)^4. - Klaus Brockhaus, Mar 20 2011
MAPLE
(10/3)*n*(n+1)*(2*n+1)
MATHEMATICA
10n(n+1)(2n+1)/3
LinearRecurrence[{4, -6, 4, -1}, {0, 20, 100, 280}, 40] (* Harvey P. Dale, Jul 18 2016 *)
PROG
(Magma) A016755:=func< n | (2*n+1)^3 >; A001845:=func< n | (2*n+1)*(2*n^2+2*n+3)/3 >; [ A016755(n)-A001845(n): n in [0..40] ]; // Klaus Brockhaus, Mar 20 2011
CROSSREFS
Sequence in context: A128676 A039455 A294112 * A027986 A240437 A174078
KEYWORD
nonn,easy
AUTHOR
Damien Pras, Mar 19 2011
STATUS
approved

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Last modified March 29 02:23 EDT 2024. Contains 371264 sequences. (Running on oeis4.)